Name: making cdna from rna templates
Uploaded: 2021-04-07T12:12:00.000Z
Duration: 1 min 44 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Biology

links-among-engineering-technology-science-and-society

Links Among Engineering, Technology, Science, and Society

BIO1.ETS2.1

Complementary DNA

- [Narratore] Quasi tutte
le cellule del corpo

hanno lo stesso DNA, ma diversi tipi

di cellule, come neuroni
e cellule muscolari,

esprimono geni diversi
perché solo determinati geni

sono trascritti in RNA messaggero,
o mRNA, in ogni cellula.

In laboratorio gli mRNA
sono utilizzati come modello

per sintetizzare l'DNA gratuito, cDNA,

per studiare l'espressione genica.

Un metodo comune è quello di
estrarre l'RNA dalle cellule,

quindi isolare l'mRNA
da altri tipi di RNA,

come l'RNA ribosomiale o l'RNA transfer,

eseguendo il campione
su una colonna di perle

con tratti di nucleotidi
di timina attaccati.

Questi si legano alla coda Poly (A),

una catena di nucleotidi
adenina specificamente presente

sui tre estremi dell'mRNA eucariotico.

Gli altri tipi di RNA non si
legano e vengono lavati via.

Dopo che l'mRNA è stato
isolato, un primer Poly (T)

è legato alla coda Poly (A),
fornendo un punto di partenza

per gli enzimi della trascrittasi inversa

per trascrivere un singolo
filamento in cDNA dall'mRNA.

Vengono aggiunti prodotti
chimici come gli enzimi RNasi

per degradare l'RNA.

Vengono quindi utilizzati
enzimi DNA polimerasi

sintetizzare un filo
complementare al cDNA,

risultante in cDNA a doppio filamento,

che può essere inserito in
un vettore batterico o virale

e utilizzato nella ricerca
di biologia molecolare.

Pray, Leslie A. "La rivoluzione biotecnologica: PCR e l'uso della trascrittasi inversa per clonare geni espressi". Educazione alla natura 1, n. 1 (2008): 94. [<a href="https://www.nature.com/scitable/topicpage/the-biotechnology-revolution-pcr-and-the-use-553" target="__blank">Sorgente</a>]

dna complementare

<h4>Panoramica</h4>

Solo i geni trascritti in RNA messaggero (mRNA) sono attivi o espressi. Gli scienziati possono, quindi, estrarre l'mRNA dalle cellule per studiare l'espressione genica in diverse cellule e tessuti. Lo scienziato converte l'mRNA in DNA complementare (cDNA) attraverso la trascrizione inversa. Poiché l'mRNA non contiene introni (regioni non codificanti) e altre sequenze regolatorie, il cDNA, a differenza del DNA genomico, consente anche ai ricercatori di determinare direttamente la sequenza di amminoacidi del peptide codificato dal gene.

<h4>sintesi cDNA</h4>

il cDNA può essere generato con diversi metodi, ma un modo comune è quello di estrarre prima l'RNA totale dalle cellule, e quindi isolare l'mRNA dai tipi più predominanti: RNA di trasferimento (tRNA) e ribosomale (rRNA). L'mRNA eucariotico maturo ha una coda poli(A), una stringa di nucleotidi di adenina, aggiunta alla sua estremità 3', mentre altri tipi di RNA no. Pertanto, una stringa di nucleotidi di timina (oligo-dT) può essere attaccata a un substrato come una colonna o perline magnetiche, in modo specifico coppia di base con le code poli(A) di mRNA. Mentre l'mRNA con una coda poli(A) viene catturata, gli altri tipi di RNA vengono lavati via.

Successivamente, la trascrizione inversa, un enzima di polimerasi del DNA proveniente da retrovirus, viene utilizzata per generare cDNA dall'mRNA. Poiché, come la maggior parte delle polimerasi del DNA, la trascrizione inversa può aggiungere nucleotidi solo all'estremità 3' di una catena, viene aggiunto un primer poli(T) da associare alla coda poli(A) per fornire un punto di partenza per la sintesi cDNA. Il filocila cDNA termina in un ciclo di tornante. L'RNA viene quindi degradato, comunemente con il trattamento con alcali o enzimi RNAsi, lasciando intatto il cDNA a singolo filamento.

Un secondo filamento di DNA complementare al cDNA viene quindi sintetizzato dalla polimerasi del DNA, spesso usando il ciclo del primo filamento cDNA o un pezzo nicked dell'mRNA come primer.

Il cDNA a doppio filamento risultante può essere inserito in vettori batterici o virali e clonati utilizzando tecniche di biologia molecolare standard. Una libreria cDNA, che rappresenta tutti gli mRNA nelle cellule o nel tessuto di interesse, può anche essere costruita per ulteriori ricerche.

DNA complementare

Overview

Only genes that are transcribed into messenger RNA (mRNA) are active, or expressed. Scientists can, therefore, extract the mRNA from cells to ...

Education

Didattica

JoVE Core

Molecular Biology

Biologia Molecolare

Unit 2

Unità 2

Studying DNA and RNA

Studiare il DNA e l'RNA

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

making cdna from rna templates

Complementary DNA, or cDNA, is made from an RNA template. It is a DNA copy of RNA, so it can help students study gene expression in a lab setting.

cDNA is useful when scientists want to work with genes after they have been turned on in a cell. Because it is copied from RNA, it reflects which genes were active at the time the RNA was collected.

This process links RNA and DNA in a simple way. It also gives students a clear view of how genetic information can be copied for analysis.

Making cDNA from RNA Templates

recombinant dna

Recombinant DNA and Gene Cloning

Recombinant DNA and gene cloning are tools used to combine DNA from different sources. Scientists use them to isolate a gene, join it to a carrier DNA molecule, and make copies of that DNA. A plasmid is one common carrier used in this process. A plasmid is a small ring of DNA found in bacteria, and it can carry the inserted gene into a host cell. Once inside the cell, the recombinant DNA can be copied as the cell grows. This approach is important in biotechnology and genetic research. It...

dna isolation

Genomic DNA Extraction Methods

Genomic DNA extraction methods separate DNA from proteins, RNA, and other cell material. The process usually follows four main steps. First, the cell structure is disrupted with mechanical or chemical methods to make a cell lysate. Then the DNA is protected from damage during processing. After that, the soluble DNA is separated from cell debris. Finally, the purified DNA is eluted, or washed out, for later use. DNA isolation can follow two main approaches: solution-based methods or solid-phase...

dna agarose gel electrophoresis

Purifying DNA Bands from Agarose Gels

Agarose gel electrophoresis can be used to purify DNA bands after separation by size. In gel extraction, the DNA fragment of interest is cut from the gel and cleaned before later use. This is especially useful in cloning, where pure DNA is needed before ligation, the joining step that links DNA pieces together. In cloning experiments, both the insert and vector DNA fragments are first cut with restriction endonucleases. These fragments often contain enzymes, salts, and other contaminants. Such...

labeling dna probes

DNA Probe Labels for Detecting Targets

DNA probes are short DNA fragments with a reporter tag attached so they can be detected or purified. They bind to matching nucleic acid sequences by complementary base-pairing. That binding helps researchers recover or identify specific regions of DNA. Several reporter tags are commonly used to label DNA probes. These include radioisotopes, fluorophores, and small molecule binding partners such as biotin or digoxigenin. The label choice depends on the probe’s intended use and on the source of...

southern blot

Southern Blot for DNA Detection

Southern blotting is a DNA detection method used after agarose gel electrophoresis separates DNA fragments by size. A DNA ladder with fragments of known length is run beside the sample so the fragment size can be estimated. The blot adds another step when scientists need to confirm the sequence identity of the DNA. First, the target DNA is cut into smaller pieces with a restriction endonuclease and run on an agarose gel. The DNA is then denatured, which means the double strands are separated...

dna microarrays

Gene Chips for Comparing Cell Activity

DNA microarrays are gene chips used to compare gene activity in different conditions. They are high-throughput assays, which means they can analyze large amounts of data at once. They are also relatively inexpensive and can be automated, making them useful for genome-wide studies. These chips are built on glass or silica slides. Probe molecules are covalently attached to the surface through surface functionalization. In many cases, the slides are prepared by chemisorption of silanes to silica...

complementary dna

Complementary DNA, or cDNA, is made from an RNA template. It is a DNA copy of RNA, so it can help students study gene expression in a lab setting. cDNA is useful when scientists want to work with genes after they have been turned on in a cell. Because it is copied from RNA, it reflects which genes were active at the time the RNA was collected. This process links RNA and DNA in a simple way. It also gives students a clear view of how genetic information can be copied for analysis.

fish - fluorescent in-situ hybridization

FISH for Chromosome and Pathogen Detection

FISH is a DNA and RNA detection method used in cytogenetics and medical testing. FISH stands for fluorescence in situ hybridization. It uses labeled probes that bind to complementary DNA or RNA sequences on a chromosome or inside a cell. The method was developed in the early 1980s and became widely used because it can show specific genetic targets with high detail. In the past, probes were made by cloning or by reverse transcription of a DNA template. Today, probe oligonucleotides can also be...

pcr - polymerase chain reaction

PCR: DNA Amplification for Genetics Labs

PCR is a DNA amplification method used in genetics labs. PCR stands for polymerase chain reaction. It copies a specific DNA segment so scientists can study small amounts of genetic material. The process uses repeated heating and cooling steps. These steps let the DNA strands separate, primers bind to the target region, and a DNA polymerase build new strands. With each cycle, the target DNA can increase in amount. PCR is a core technique in molecular biology and many school-level biology...

real time rt-pcr

Real-Time RT-PCR for Gene Expression Tracking

Real-time RT-PCR tracks gene expression by measuring how much target DNA is made during PCR. It starts with mRNA, which is converted into complementary DNA, or cDNA, by an enzyme called reverse transcriptase. The cDNA is then amplified by PCR so the target sequence can be measured. This method can be done in one tube as a single-step reaction or in two separate steps. During amplification, the amount of product is followed in real time with fluorescent dyes or sequence-specific probes linked...

race - rapid amplification of cdna ends

Finding cDNA Ends with RACE PCR

Rapid Amplification of cDNA Ends, or RACE, helps scientists capture the full-length cDNA from an mRNA sequence. It works by linking a known internal region to the unknown sequence at either the 5' end or the 3' end. The method is widely used when the missing end of a gene needs to be identified. RACE uses a gene-specific primer that binds to the known cDNA region. A hybrid primer then adds a set anchor sequence to the unknown end of the cDNA. After that, PCR amplifies the DNA segment between...

sanger sequencing

How Sanger Sequencing Reads DNA Fragments

Sanger sequencing reads DNA fragments by separating pieces of different lengths and decoding the order of bases. It is a key method in biology and is often used to study a cloned DNA fragment, a gene mutation, or even much larger genomes. Fredrick Sanger and his collaborators developed the chain-termination method in 1977. The method works by producing a mixture of DNA fragments with variable sizes. These fragments are then separated by capillary gel electrophoresis, which sorts them by length.

next-generation sequencing

DNA Sequencing Methods and Uses

DNA sequencing methods can read millions of DNA fragments at the same time. Next-generation sequencing made this process much faster and much less expensive than older methods. The first human genome project cost $2.7 billion and took 15 years. It was completed in 2003 after major international cooperation among research teams and funding agencies. To prepare DNA for next-generation sequencing, pure genomic DNA is first broken into smaller pieces. These pieces are used to build a sequencing...

rna-seq

RNA-Seq Workflow and Data Analysis

RNA sequencing, or RNA-Seq, is a high-throughput method for studying the transcriptome of a cell. The transcriptome is the full set of RNA molecules in a sample. Transcriptomics helps scientists understand how genomes work, how organisms develop, and how some diseases occur. Before RNA-Seq, researchers often used microarray methods and Sanger sequencing to study RNA. Microarrays had limited coverage and depended on already knowing the genome sequence. Sanger sequencing was low-throughput,...

genome annotation and assembly

How Genome Assemblies Are Updated

Genome assembly and genome annotation are key steps in genome analysis. Genome assembly puts DNA sequencing data back in the correct order to make a close copy of the original genome. Genome annotation then identifies functional parts on that assembled genome. Assembling a genome is not simple. In human populations, gene copy number can vary, and repeated DNA sequences can make the process harder. Even so, the physical location of human genes stays constant. Bacterial genomes can be more...

restriction enzymes

DNA Cutting Sites and Bacterial Defense

Restriction enzymes are bacterial proteins that cut DNA at specific sequence sites. They recognize palindromic DNA sequences, also called inverted repeats, and cut the DNA in a sequence-specific way. These sites are often found in regions with important functions, such as the origin of replication, gene operator sites, and transcription termination signals. Bacteria protect their own DNA by methylating these same sites. Methylation means adding chemical marks that keep the restriction enzyme...

maxam-gilbert sequencing

Chemical Cleavage DNA Sequencing

Chemical cleavage DNA sequencing uses specific chemicals to cut DNA at known sites. Allan Maxam and Walter Gilbert described this method in the same year that the Sanger sequencing method was discovered. It reads the DNA sequence by breaking purified DNA into fragments and then studying the fragment pattern. The method depends on chemicals that cleave DNA at specific bases. The resulting fragments are separated by electrophoresis, which is a way to sort DNA pieces by size using an electric...

key terms and concepts

Learn how complementary DNA, or cDNA, is made from an RNA template and how it helps scientists study gene expression in the lab.

Making cDNA from RNA Templates | JoVE K12

molecular biology

Le video animazioni di JoVE Core Molecular Biology, organizzate in video lezioni, illustrano i processi molecolari cellulari in maniera chiara e concisa. Inoltre, nei video di "scienziati in azione", i concetti scientifici vengono applicati e dimostrati da ricercatori attraverso esperimenti in laboratorio.

Texas Essential Knowledge and Skills

BIO.7

BIO.7.D

myJoVE Corporation

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Recombineering and Gene Targeting

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Genome Editing

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Restriction Enzyme Digests

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DNA Isolation

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Restriction Enzymes

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DNA Agarose Gel Electrophoresis

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Gel Purification

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PCR - Polymerase Chain Reaction

Real Time RT-PCR

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RACE - Rapid Amplification of cDNA Ends

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PCR: The Polymerase Chain Reaction

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bacterial-transformation-the-heat-shock-method

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An Introduction to Transfection

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Labeling DNA Probes

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Southern Blot

Agarose gel electrophoresis is very useful in separating DNA fragments by size. Running a DNA ladder containing fragments of the known length alongside ...

DNA Microarrays

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An Overview of Gene Expression

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Expression Profiling with Microarrays

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FISH - Fluorescent In-situ Hybridization

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Sanger Sequencing

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Maxam-Gilbert Sequencing

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Next-generation Sequencing

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Chromatin Immunoprecipitation- ChIP

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RNA-seq

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Synthetic Biology

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Genome Annotation and Assembly

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Ribosome Profiling

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The ELISA Method

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Transgenic Plants

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Transgenic Organisms

Gene Therapy

Reproductive Cloning

CRISPR

Experimental RNAi

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Reporter Genes

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In-situ Hybridization

In situ hybridization (ISH) is a technique used to detect and localize specific DNA or RNA molecules in cells, tissue, or tissue sections using a labeled ...

Obtain, evaluate, and communicate information on how molecular biotechnology may be used in a variety of fields.
EXPLANATION: The goal is to help students appreciate that the basic science knowledge being studied can be manipulated and used to design useful tools for further scientific investigations, medical treatments, agricultural yields, etc. A detailed understanding of any technical procedures is not expected, but rather a "big picture" view of concepts the technology utilizes and the applications the technology is being used for. These technologies may be best investigated along with the standards from LS1 From Molecules to Organisms: Structure and Functions, as the students are learning about DNA and protein. Comparative DNA and protein sequence analysis is also a large part of current phylogenic research and could accompany LS4 Biological Change: Unity and Diversity. Students may also consider the pros and cons of biotechnical applications. Investigation of techniques utilized could come from field trips to witness the use of these techniques in practice, lab exercises, virtual labs, simulation activities, interviews with professionals, etc. Molecular techniques could include: PCR, electrophoresis, restriction enzyme digestion of DNA, DNA sequencing, plasmid-based transformation, transfection, etc. These techniques are used in fields of medicine, agriculture, biomedical engineering, forensic science, etc.

Karyotyping

Lampbrush Chromosomes

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Polytene Chromosomes

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Euchromatin

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Heterochromatin

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Investigate means by which karyotypes are utilized in diagnostic medicine.
EXPLANATION: Engineers incorporate growing scientific knowledge in order to increase benefits to humans and decrease cost and risks. Karyotyping technology and its use in medical diagnosis can complement the standards from LS3: Hereditary: Inheritance, and Variation of Traits, as the students are learning about chromosomal organization of genomic information that determines one's phenotype. Analyze a large set of karyotypes to identify common patterns. Identify variations from the most commonly observed patterns and correlate them with patient phenotypes to propose a cause and effect relationship, discussing limitations of correlative data interpretation.

BIO1.ETS2.2

Whole Body Regeneration

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Introduction to Nuclear Reprogramming

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Methods of Nuclear Reprogramming

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Analyze scientific and ethical arguments to support the pros and cons of applications of a specific biotechnology technique such as stem cell usage, in vitro fertilization, or genetically modified organisms.
EXPLANATION: The utilization of new technologies in any field of science is dependent on both economic and social factors. In addition to evaluating these factors, scientists must also consider long-term consequences that may not be initially apparent. The emphasis should be on the construction of a rationale argument that supports a position on the use of an application with ethical and social impact. Students should begin to appreciate the differences in ethical values that exist, and recognize that discussion of these values is imperative as knowledge and technology continue to advance, even when resolutions of differences can be rare. After investigation of a specific biotechnology application, students can write a position paper and/or participate in a classroom debate.

BIO1.ETS2.3

Making cDNA from RNA Templates

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